Alloy



Patented Aug 16, 1938 i p UNITED ALLOY Anthony G. de GoLver, New York,N. Y.

.No Drawing. Application April 17, 1936,-

Serial No. 75,020

3 Claims.

The present invention relates to a new and useful alloy and relatesparticularly to an alloy con taining as essential components boron,zirconium, tungsten and cobalt, which has a high degree of 5 hardnessand other valuable properties.

This application is a continuation, in part, of my co-pendingapplication, Serial No. 720,203, filed on April 12, 1934.

An object of the present invention is to pro- 10 vide an alloyespecially adapted for use as metal ,cutting or forming tools, thecutting emciency of which is several times greater than that of presentknown high speed steels and other alloys. A further object of thisinvention is to provide if; an alloy which is free from, orsubstantially free from parbon and which is readily amenable to thermaltreatment, by means of which the hard ness, tensile strength, cuttingefiiciencyand other physical properties and characteristics may be 20accurately controlled over a comparatively wide' range.

I have found through experiment that by alloying or otherwise intimatelycombining bron,.

zirconium, tungsten and cobalt within the range 2 boron from 0. 50% to5%, zirconium 1.50% to 20%, tungsten to 40% and cobalt substantially thebalance, that I obtain metallic compositions which possess incombination materially improved physical properties compared .to thoseof heretofore known alloys or compositions intended for the cutting orworking of metals.

Alloys of this invention may be used in the cast condition butapproximate maximum values of hardness and certain other importantphysical properties can be developed only through thermal treatment, orthrough mechanical working and subsequent thermal treatment; Bodies ofthe alloys which have been subiected to such treatment are particularlyvaluable for use as tools,

' i dies and the like for the cutting or mechanical working of metals.

Numerous metallic compositions have heretofore been proposed asimprovement on the generally known 18-4-1 type of tungsten-chromium- 5vanadium high speed tool steel, and while many of such compositionspossess greater hardness than such steel, all of them have disadvantageswhich render them unsuitable for general application as metal cutting ori'orming tools. For

50 example, sintered or fused compositions containing principallycarbides of tungsten, molybdenum or tantalum bonded with a relativelysoft matrix metal have a high degree of hardness, but all of these areextremely brittle. Another disadvantage 55 is that such materials, whenoperated as metal cutting tools at high speed, have a tendency tocrater, i. e. to be worn away by contact with hot metal chips. Castcompositions such as the type comprising principally chromium, tungstenand cobalt, require the presence of at least 1.50% car- 5 ban to qualifyas metal cutting tools, and, as is well known, such alloys are not onlybrittle, but are so sensitive to various operating conditions as togreatly restrict the scope of usefulness. One of the greatestdisadvantages of virtually all of in the heretofore suggestedcompositions is that none of them are responsive to thermal'treatmentfor regulation of physical properties, and consequently physicalproperties and characteristics are governed entirely by the chemicalcomposition of the w material. I

My alloy may be used in the as-nst condition, or it may be forged androlled'or otherwise mechanically worked. I have found that both the castand forged material are amenable to ther- 90 .mal treatment. Forexampule, castor forged bodies of this alloy may have a hardness of from54 to 61 on the Rockwell C. scale and by subjecting the material tosuitable thermal treatment, such as quenching from a temperature higher35 than 1000 'C., the hardness may be lowered to an approximate range offrom 42 to 49 Rockwell C. In this condition the bodies may be ground,shaped or formed, if desired. The alloy may subsequently be submitted toa second thermal treatment, such as heating to a temperature of lessthan 1000 C. for a period of from one or more hours, by which thehardness may be increased to from approximately 60 to 70 Rockwell C. Inthe latter condition the alloy is especially valuable for the cutting ormechanical working of a large number of metals and alloyspas well asnumerous non-metallic materials. An important I property of the alloy isthat virtually all of the maximum hardness, developed by thermaltreatment, is retained when the alloy is subjected to elevatedtemperatures. e. g. such as are generated in the tip of a tool cuttingmetal at high speed. Another outstanding advantage is that 65 when thealloy of the present invention is used as a metal cutting tool, neitherthe tip nor any portion of the tool is burned or cratered by hot metalchips resulting from the cutting operation. Further hot chips do notadhere to the tool re- 50 gardless oi the speed at which it may beoperated. In addition, the alloy is markedly re-.

, sistant to oxidation and corrosion at both normal and elevatedtemperatures. Although the alloy has a high degree of hardness.especially after thermal treatment, it is remarkably resistant tofailure from sudden or repeated shock.

The more important distinctive and valuable advantages are, apparently;due to the presence of appreciable amounts of boron in the composition,

in conjunction with the other essential component elements within thepercentages specified herein- 1 Although I usually prefer'to -have thealloy which is to be used as a metal cutting tool, for example composedprincipally of boron, zirconium, tungsten and cobalt, I have found thatin many instances the tungsten may be supplanted in whole or in part bymolybdenum or uranium,

\ or both. The results of my investigations indicate that alloyscomposed principally of boron 0.50% to 5%, zirconium 1.50% to 20%, metalfrom the group molybdenum and uranium to 40% and the balance cobalt,possess substantially the same valuable physical properties andcharacteristics as the above described composition containing onlytungsten in combination with boron, zirconium and cobalt. Therefore, thealloy. of my present invention comprises boron 0.50% to-5%, zirconium1.50% to 20%, metal selected from the group tungsten, molybdenum anduranium 10% to 40% and the balance cobalt.

Specific examples of compositions within, the

scope oi the present invention which I have found well adapted for useas metal cutting tools are the following: boron 1.40%, zirconium 7%,

tungsten 12%, cobalt balance; boron 2.30%, zirconium 3%, tungsten14.50%, cobalt balance; boron 1.20%, zirconium 9.50%, tungsten 19%,cobalt balance; boron 2.15%, zirconium 13%, mo-

. lybclenum 12%, cobalt balance; boron 1.35%, zir

conium 3%, tungsten 4%, molybdenum 10%,

I cobalt balance.

An objective of the present invention is to proa maximum of about 0.15%,as I have found that the presence of higher percentages of this elementnot only tend to embrittle the alloy, but

,stituent in the nature of an eutectoid.

My investigations indicate that the preferred structure of a body of thepresent alloy, particularlyafter thermal treatment, comprises at leasttwo principal constituents: one, a relatively hard intermetalliccompound of boron with one or more of the other essential components;and, second, a solid solution of two or more of the essential componentswhich has a lower degree of hardness and functions as a matrix. In someinstances the structure will contain a third con- The ratio of theconstituents in any particular body of the alloy may be accuratelycontrolled and fixed over a wide range by means of thermal treatment, ormechanical working and subsequent thermal treatment.

By reason of the combined advantageous physical properties possessed bythe alloy of the present invention, tools and other articles composed ofthis alloy may be operated emciently and economically under conditionswhich are impossible or uneconomical with tools or articles composed ofheretofore known alloys or metallic compositions.

It will be understood that theelement vanadium may be added to the alloyof the present invention in an amount from approximately 0.25% to 2.50%but the inclusion of this element does not improve any of the physicalproperties.

. I claim:

1. Aprecipitation hardened alloy consisting of boron 0.50% to 5%,zirconium 1.50% to 20%, metal from the group tungsten, molybdenum anduranium 10% to 40%, the balance cobalt.

2. A precipitation hardened alloy consisting of boron 0.50% to 5%,zirconium 1.50% to 20%, tungsten 10% to 40%, the balance cobalt.

3. A precipitation hardened alloy consisting of boron 0.50% to 5%,zirconium 1.50% to 20%, molybdenum 10% to 40%, the balance cobalt.

ANTHONY G. pa GOLYER.

